U.S. Pat. No. 4,340,316, issued Jul. 12, 1982, to Gerhard Jahn describes a paper binder including a cover portion having a spine fitted with interlocking male and female members to receive punched paper. The female members and the male members are provided on individual pieces of plastic separately secured at the spine of the binder.
The above system relies on a relatively heavy duty cover having a spine provided with preformed folds allowing the male and female parts to come together with one another. In addition and because the male and female parts are mounted independently of one another to the cover, it is possible to improperly assemble the binder such that the posts on the male member do not properly align with the recesses on the female member preventing the binder from closing.
From an inventory control standpoint, when working with two independent parts, i.e. the male and the female parts, it is possible that one of the parts can be lost rendering the other part useless.